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HiTech's avatar
HiTech
Explorer
Dec 14, 2012

Measuring solar yield approaching winter solstice

I need to get a temporary setup on the RV roof to measure solar yield around the winter solstice. How deeply discharged will I need to get my 85 Ah battery so that it allows pretty full production ...
CA_Traveler's avatar
CA_Traveler
Explorer III
Dec 15, 2012
red31 wrote:
Turn on one light at dusk and try.

2-3 kWh/m^2/day, so 3*4amp = 12ah/day
http://rredc.nrel.gov/solar/old_data/nsrdb/1961-1990/redbook/atlas/
Is this for a particular panel or just how do you in general intrepret the NREL charts for a reasonable estimate of solar power?

I would have thought that for Texas n December iwith 2-3 kWh/m^2/day one could use:
2500W (average)*14% (panel efficiency) = 350W/14V (battery voltage) = 25AH for one day for a 1 m^2 sized panel.

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